Modified humic acid as well as preparation method and application thereof

Abstract

The invention provides modified humic acid as well as a preparation method and application thereof. The modified humic acid is prepared from the following raw materials: humic acid, a carbonizer, a nitrating agent and a sulfonating agent. According to the invention, humic acid is subjected to carbonization, nitration and sulfonation treatment, such that modified humic acid is obtained. The modified humic acid disclosed by the invention can be used as an adsorbent for treating low-concentration ammonia nitrogen wastewater, can effectively adsorb and remove ammonia nitrogen and organic nitrogen, and reduces secondary pollution of a water environment; according to the method, raw materials are easy to obtain, preparation is simple, the modified humic acid has higher active functional group content, and when the modified humic acid serves as a synergist, the effect of the modified humic acid in the aspects of soil improvement and fertilizer synergism can be enhanced.

Description

Technical Field

[0001] The present invention relates to the modification technology of humic acid, and particularly to a modified humic acid, its preparation method and application. Background Art

[0002] With the rapid development of industrialization and urbanization, environmental pollution problems are becoming increasingly serious. Among them, water pollution, especially the discharge of ammonia-nitrogen wastewater, poses a huge threat to the ecological environment and human health. At the same time, the decline in soil quality also affects the sustainable development of agriculture. Finding efficient, environmentally friendly and economical solutions is extremely urgent. As a natural organic substance, humic acid has unique structures and properties, showing potential application values in the fields of environmental governance and agriculture.

[0003] Humic acid is a natural organic macromolecule substance widely existing in nature, mainly formed by the decomposition and transformation of plant residues by microorganisms and a series of geochemical processes. Its structure is complex, containing various functional groups such as carboxyl groups, phenolic hydroxyl groups, alcoholic hydroxyl groups, carbonyl groups, methoxy groups, etc. These functional groups endow humic acid with good ion exchangeability, adsorption, complexation and biological activity. The molecular weight distribution of humic acid is relatively wide, ranging from several hundred to several hundred thousand, and its molecular structure is an irregular network with a large specific surface area, enabling it to interact with various substances.

[0004] In the industrial field, a large amount of ammonia-nitrogen-containing wastewater is generated during the production processes of industries such as chemical engineering, pharmaceuticals, food processing, and printing and dyeing. After the ammonia-nitrogen wastewater is discharged into water bodies, it will cause eutrophication of water bodies. Under certain conditions, ammonia nitrogen will be converted into nitrite, which has carcinogenic, teratogenic and mutagenic effects and poses a potential threat to human health; in industrial production, such as in industries like power and chemical engineering, when using ammonia-nitrogen-containing water as cooling water or process water, ammonia nitrogen will form scale on the surface of equipment, reducing the heat transfer efficiency of the equipment, increasing energy consumption, and at the same time causing corrosion of the equipment, shortening the service life of the equipment and increasing production costs. In the agricultural field, the complexation stability between natural humic acid and medium and trace element fertilizers is insufficient, and it cannot well maintain the medium and trace elements in a state that can be absorbed and utilized by plants, affecting the comprehensive supply of plant nutrients and being unfavorable for improving the yield and quality of crops. In terms of the limitation of the soil improvement effect in improving the soil structure, the improvement effects of natural humic acid on different types of soils are different and not lasting enough.

[0005] Due to the rich functional groups and large specific surface area of humic acid, it has good adsorption properties for heavy metal ions, organic pollutants, etc. In wastewater treatment, humic acid can be used as an adsorbent to remove heavy metal ions such as lead, mercury, cadmium, chromium, etc. in wastewater. Through ion exchange and complexation, the heavy metal ions are fixed on the surface of humic acid, thus achieving the purpose of removal. At the same time, humic acid also has a certain adsorption capacity for organic pollutants such as phenols, pesticides, dyes, etc., which can reduce the concentration of organic pollutants in wastewater and alleviate water pollution. Although humic acid has certain adsorption properties and ion exchange properties, when directly used to treat low-concentration ammonia nitrogen wastewater, there are problems such as slow adsorption rate and poor enrichment effect. This is because the surface functional groups of humic acid have low activity, the binding ability with ammonia nitrogen is limited, and the molecular structure of humic acid is relatively complex, and some functional groups are wrapped inside the molecule, making it difficult to fully interact with ammonia nitrogen. In addition, the effects of humic acid in soil improvement and fertilizer efficiency enhancement are also limited by its own structure and properties, and it is necessary to further increase the content of its active functional groups to enhance its application effects in these aspects.

[0006] In summary, due to the above-mentioned many limitations of natural humic acid in the environmental protection and agricultural fields, developing a humic acid with higher active functional groups, which can effectively adsorb and remove ammonia nitrogen and organic nitrogen when treating low-concentration ammonia nitrogen wastewater, reduce the secondary pollution of the water environment, and enhance its effects in soil improvement and fertilizer efficiency enhancement is the problem to be solved by the present invention. Summary of the Invention

[0007] The purpose of the present invention is to provide a modified humic acid, which can be used as an adsorbent to treat low-concentration ammonia nitrogen wastewater, can effectively adsorb and remove ammonia nitrogen and organic nitrogen, and reduce the secondary pollution of the water environment; the raw materials of this method are easy to obtain and the preparation is simple, and the modified humic acid has a higher content of active functional groups. When used as a synergist, it can enhance its effects in soil improvement and fertilizer efficiency enhancement.

[0008] In order to achieve the above technical purpose, the present invention provides a modified humic acid. The raw materials for preparing the modified humic acid include the following components: humic acid, carbonizing agent, nitrating agent, sulfonating agent.

[0009] Further, the humic acid is one or a mixture of weathered coal humic acid, lignite humic acid, and peat humic acid.

[0010] Further, the nitrating agent is a mixture of potassium nitrate and concentrated sulfuric acid, and the mass ratio of potassium nitrate to concentrated sulfuric acid is 1-2:1.

[0011] Further, the sulfonating agent is a mixture of sulfur trioxide and concentrated sulfuric acid, and the mass ratio of sulfur trioxide to concentrated sulfuric acid is 1-3:1.

[0012] The present invention also provides a method for preparing modified humic acid, which is characterized by comprising the following steps:

[0013] S1: Put the carbonizing agent into a reaction kettle, slowly drop the humic acid into the reaction kettle, and stir and react at 100-150 °C for 2-4 h;

[0014] S2: After the reaction in step S1 is completed, cool the reaction mixture to room temperature, then slowly pour it into a large amount of ice water for dilution, then filter and wash to make the pH value of the reactant 7-9, and then dry it in a vacuum drying oven at 60-80 °C for 12-24 hours to obtain carbonized humic acid;

[0015] S3: Put the nitrating agent into another reaction kettle, slowly drop the carbonized humic acid prepared in step S2 into the reaction kettle, and stir and react at 0-5 °C for 1-2 h;

[0016] S4: After the reaction in step S3 is completed, pour the reaction mixture into ice water for dilution to precipitate the nitration product, filter and wash until the pH value is 7-9 to obtain nitro humic acid;

[0017] S5: Put the sulfonating agent into another reaction kettle, slowly drop the nitro humic acid prepared in step S4 into the reaction kettle, and stir and react at 80-120 °C for 3-5 h;

[0018] S6: After the reaction in step S5 is completed, cool the reaction mixture to room temperature, then slowly pour it into a large amount of ice water for dilution, then filter and wash until the pH value of the mixture is 7-9, and then dry it in a vacuum drying oven at 60-80 °C for 12-24 hours to obtain modified humic acid.

[0019] Further, the mass ratio of the humic acid to the carbonizing agent in step S1 is 1:3-5; the carbonizing agent is concentrated sulfuric acid.

[0020] Further, the mass ratio of the carbonized humic acid to the nitrating agent in step S3 is 1:1.5-3.

[0021] Further, the mass ratio of the nitro humic acid to the sulfonating agent in step S5 is 1:0.8-2.

[0022] The present invention also provides the application of modified humic acid. The modified humic acid, sulfonated humic acid, and iron-loaded humic acid are compounded as an adsorbent for treating low-concentration ammonia nitrogen wastewater.

[0023] The present invention also provides the application of modified humic acid. The modified humic acid is compounded with chelated trace elements as a synergist for improving soil and enhancing fertilizer efficiency.

[0024] The present invention obtains modified humic acid by carbonizing, nitrating and sulfonating humic acid. This method uses easily obtainable raw materials, is simple to prepare, and the modified humic acid has a higher content of active functional groups, enhancing its effects in soil improvement and fertilizer efficiency enhancement.

[0025] Beneficial effects:

[0026] The modified humic acid of the present invention can be used as an adsorbent to treat low-concentration ammonia nitrogen wastewater. When compounded with the modified humic acid adsorbent, it can effectively adsorb and remove ammonia nitrogen and organic nitrogen in low-concentration ammonia nitrogen wastewater, reducing secondary pollution of the water environment; the modified humic acid fertilizer synergist, by adding chelated trace elements, increases the content of water-retaining and fertilizer-increasing active functional groups of humic acid, improving the yield of crops. Specific embodiments

[0027] The following will illustrate the present invention in conjunction with specific implementation schemes. It should be noted that the following examples are examples of the present invention, only used to illustrate the present invention, and not to limit the present invention. Without departing from the gist or scope of the present invention, other combinations and various improvements within the concept of the present invention can be made.

[0028] Unless otherwise specified, the chemical reagents used in the present invention are all ordinary commercially available analytical pure.

[0029] Weathered coal humic acid is purchased from Guangzhou Yingfeng Trading Co., Ltd.; lignite humic acid is purchased from Inner Mongolia Humic Acid Professional Processing Factory.

[0030] The preparation of modified humic acid A includes the following steps:

[0031] S1: Put 5 kg of concentrated sulfuric acid into a reaction kettle, slowly drop 1 kg of weathered coal humic acid into the reaction kettle, and stir and react at 120 °C for 4 h;

[0032] After the reaction in step S1 is completed, cool the reaction mixture to room temperature, then slowly pour it into a large amount of ice water for dilution, then filter and wash until the pH value of the reactant is 8, and then dry it in a vacuum drying oven at 60 °C for 24 hours to obtain carbonized humic acid;

[0033] S3: Put 1.6 kg of nitrating agent (a mixture of potassium nitrate and concentrated sulfuric acid with a mass ratio of 2:1) into another reaction kettle, and slowly drop 0.8 kg of carbonized humic acid prepared in step S2 into the reaction kettle, and stir and react at 0 °C for 2 h;

[0034] After the reaction in step S3 is completed, pour the reaction mixture into ice water for dilution to precipitate the nitration product, and after filtration and washing until the pH value is 7, nitro humic acid is obtained;

[0035] S5: Put 1 kg of sulfonating agent (sulfur trioxide and concentrated sulfuric acid mixed at a mass ratio of 3:1) into another reactor, and slowly drop 0.5 kg of nitrohumic acid prepared in step S4 into the reactor, and stir and react at 100 °C for 4 h;

[0036] S6: After the reaction in step S5 is completed, cool the reaction mixture to room temperature, then slowly pour it into a large amount of ice water for dilution, then filter and wash until the pH value of the mixture is 7.5, and then dry it in a vacuum drying oven at 60 °C for 24 hours to obtain modified humic acid A.

[0037] Preparation of modified humic acid B:

[0038] The difference between the modified humic acid B and the modified humic acid A is as follows: In step S1, 5 kg of concentrated sulfuric acid is replaced by 3 kg; in step S3, 1.6 kg of nitrating agent (potassium nitrate and concentrated sulfuric acid mixed at a mass ratio of 2:1) is replaced by 2.4 kg of nitrating agent (potassium nitrate and concentrated sulfuric acid mixed at a mass ratio of 1:1); in step S5, 1 kg of sulfonating agent (sulfur trioxide and concentrated sulfuric acid mixed at a mass ratio of 2:1) is replaced by 0.4 kg of sulfonating agent (sulfur trioxide and concentrated sulfuric acid mixed at a mass ratio of 1:1).

[0039] Preparation of modified humic acid C:

[0040] The difference between the modified humic acid C and the modified humic acid A is as follows: In step S1, 5 kg of concentrated sulfuric acid is replaced by 2 kg; in step S3, 1.6 kg of nitrating agent (potassium nitrate and concentrated sulfuric acid mixed at a mass ratio of 2:1) is replaced by 1.6 kg of nitrating agent (potassium nitrate and concentrated sulfuric acid mixed at a mass ratio of 0.5:1); in step S5, 1 kg of sulfonating agent (sulfur trioxide and concentrated sulfuric acid mixed at a mass ratio of 2:1) is replaced by 1 kg of sulfonating agent (sulfur trioxide and concentrated sulfuric acid mixed at a mass ratio of 1:2).

[0041] Preparation of sulfonated humic acid: Put 3 kg of concentrated sulfuric acid into a reactor, slowly drop 1 kg of lignite humic acid into the reactor, stir and react at 100 °C for 4 h. After the reaction is completed, cool the reaction mixture to room temperature, then slowly pour it into a large amount of ice water for dilution, then filter and wash until the pH value of the mixture is 8, and then dry it in a vacuum drying oven at 60 °C for 24 hours to obtain sulfonated humic acid.

[0042] Preparation of iron-loaded humic acid: Put 5 kg of weathered coal humic acid into a three-necked flask, pour in 5 L of sodium hydroxide solution with a concentration of 0.2 mol / L, stir to form a weathered coal humate solution, then slowly add 2.5 kg of 0.5 mol / L ferric chloride solution to the weathered coal humate solution, adjust the pH to 6, control the temperature at 30 °C, and the stirring speed at 300 revolutions per minute. Stir and react for 4 hours. After the reaction is completed, precipitate, filter, and wash the reaction solution, and then dry it to constant weight at 60 °C to obtain iron-loaded humic acid.

[0043] Example 1:

[0044] Preparation of compound modified humic acid adsorbent A:

[0045] Put sulfonated humic acid, iron-loaded humic acid, and modified humic acid A into a blender according to a mass ratio of 3:2:1, and stir at 1500 revolutions per minute for 1 - 2 hours to make the three components fully mixed and uniform, thus obtaining the compound modified humic acid adsorbent A.

[0046] Example 2:

[0047] Preparation of compound modified humic acid adsorbent B:

[0048] Put sulfonated humic acid, iron-loaded humic acid, and modified humic acid B into a blender according to a mass ratio of 5:5:1, and stir at 1500 revolutions per minute for 1 - 2 hours to make the three components fully mixed and uniform, thus obtaining the compound modified humic acid adsorbent B.

[0049] Example 3:

[0050] Preparation of compound modified humic acid adsorbent C:

[0051] Put sulfonated humic acid, iron-loaded humic acid, and modified humic acid C into a blender according to a mass ratio of 3:2:1, and stir at 1500 revolutions per minute for 1 - 2 hours to make the three components fully mixed and uniform, thus obtaining the compound modified humic acid adsorbent C.

[0052] Example 4:

[0053] Preparation of modified humic acid fertilizer synergist A:

[0054] Dissolve 1 kg of modified humic acid A in 10 L of water to form a uniform humic acid solution. Add chelated trace elements (5 g of sodium iron ethylenediaminetetraacetate, 10 g of zinc ethylenediaminetetraacetate, 15 g of manganese citrate, 10 g of copper ethylenediaminetetraacetate) to the humic acid solution one by one, and stir to make them fully mixed and uniform. The stirring speed is 400 revolutions per minute, and the stirring time is 30 minutes to obtain modified humic acid fertilizer synergist A.

[0055] Example 5:

[0056] Preparation of Modified Humic Acid Fertilizer Synergist B:

[0057] Dissolve 1 kg of modified humic acid B in 10 L of water to form a uniform humic acid solution. Add the chelated trace elements (10 g of sodium ferric ethylenediaminetetraacetate, 10 g of zinc ethylenediaminetetraacetate, 10 g of manganese citrate, 10 g of copper ethylenediaminetetraacetate) into the humic acid solution one by one, and mix them evenly. The stirring speed is 400 revolutions per minute, and the stirring time is 30 minutes to obtain the modified humic acid fertilizer synergist B.

[0058] Example 6:

[0059] Preparation of Modified Humic Acid Fertilizer Synergist C:

[0060] Dissolve 1 kg of modified humic acid C in 10 L of water to form a uniform humic acid solution. Add the chelated trace elements (5 g of sodium ferric ethylenediaminetetraacetate, 10 g of zinc ethylenediaminetetraacetate, 15 g of manganese citrate, 10 g of copper ethylenediaminetetraacetate) into the humic acid solution one by one, and mix them evenly. The stirring speed is 400 revolutions per minute, and the stirring time is 30 minutes to obtain the modified humic acid fertilizer synergist C.

[0061] Performance Test Experiment:

[0062] 1. Adsorption Performance Test:

[0063] Prepare a 10 L wastewater sample with an ammonia nitrogen concentration of 10 mg / L and an organic nitrogen concentration of 30 mg / L. Add the modified humic acid adsorbent into the wastewater at a dosage of 1 g / L. Take a sample after 15 minutes, and then measure the concentrations of ammonia nitrogen and organic nitrogen in the wastewater to judge the speed and effect of adsorption.

[0064] 2. Water Retention Performance Test:

[0065] Adopt a soil column experiment. Fill the soil columns with soil added with 1% modified humic acid fertilizer synergist as the experimental group and soil without added synergist as the control group. Plant the same corn and do not water for two weeks. Use a soil moisture sensor to measure the soil water content to observe the soil water loss situation.

[0066] 3. Fertilizer Synergistic Experiment:

[0067] Plant corn in the experimental field at a seeding density of 6000 plants per mu and a seeding depth of 5 cm. Set up a control group applying 50 kg of corn compound fertilizer with a nitrogen-phosphorus-potassium mass ratio of 1:1:1 per mu and an experimental group applying 50 kg of corn compound fertilizer containing 10% modified humic acid fertilizer synergist. Statistically analyze the annual yield per mu of corn to evaluate the effect of the synergist on crop yield increase.

[0068] Performance Test Results Table 1:

[0069] Material Ammonia nitrogen concentration in wastewater / (mg / L) Organic nitrogen concentration in wastewater / (mg / L) Blank group 10.0 30.0 Example 1 0.4 8.5 Example 2 0.5 8.6 Example 3 0.8 11.5

[0070] Performance Test Results Table 2:

[0071] Material Soil moisture content / % Annual corn yield / (kg / mu) Control group 32.5 650 Example 4 28.4 782 Example 5 28.6 778 Example 6 22.8 710

[0072] It can be seen from Tables 1 - 2 that the modified humic acid of the present invention can be used as an adsorbent for treating low - concentration ammonia - nitrogen wastewater. It has a fast adsorption rate, can effectively adsorb and remove ammonia - nitrogen and organic nitrogen, and reduce secondary pollution of the water environment. Specifically, it can be seen from the comparison between Example 3 and Example 1 that when the modified humic acid is compounded with sulfonated humic acid and iron - loaded humic acid to form a modified humic acid adsorbent, the modified humic acid prepared with unreasonable dosages of carbonizing agent, nitrating agent, and sulfonating agent will result in a weakened ability to remove ammonia - nitrogen and organic nitrogen when treating low - concentration ammonia - nitrogen wastewater, failing to achieve the expected effect. The synergist prepared from the modified humic acid of the present invention can improve the soil and enhance the fertilizer efficiency. It can be seen from the comparison between Example 6 and Example 4 that when using the modified humic acid to prepare a modified humic acid fertilizer synergist, the modified humic acid prepared with unreasonable dosages of carbonizing agent, nitrating agent, and sulfonating agent will lead to a weakened water - retaining effect of the synergist on the soil and a reduced crop yield - increasing effect of the fertilizer, failing to achieve the expected effect.

[0073] The present invention can also have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention. However, these corresponding changes and deformations should all fall within the protection scope of the appended claims of the present invention.

Claims

1. A modified humic acid, characterized in that, The raw materials for preparing the modified humic acid include the following components: humic acid, carbonizing agent, nitrating agent, and sulfonating agent.

2. The modified humic acid according to claim 1, wherein The humic acid is one or a mixture of weathered coal humic acid, lignite humic acid, and peat humic acid.

3. The modified humic acid according to claim 1, characterized in that, The nitrating agent is a mixture of potassium nitrate and concentrated sulfuric acid, and the mass ratio of potassium nitrate to concentrated sulfuric acid is 1-2:

1.

4. The modified humic acid according to claim 1, wherein The sulfonating agent is a mixture of sulfur trioxide and concentrated sulfuric acid, and the mass ratio of sulfur trioxide to concentrated sulfuric acid is 1-3:

1.

5. The preparation method of the modified humic acid according to any one of claims 1-4, characterized in that, It includes the following steps: S1: Put the carbonizing agent into the reaction kettle, slowly drop the humic acid into the reaction kettle, and stir and react at 100-150 °C for 2-4 h; S2: After the reaction in step S1 is completed, cool the reaction mixture to room temperature, then slowly pour it into a large amount of ice water for dilution, then filter and wash until the pH value of the reactant is 7-9, and then dry it in a vacuum drying oven at 60-80 °C for 12-24 hours to obtain carbonized humic acid; S3: Put the nitrating agent into another reaction kettle, slowly drop the carbonized humic acid prepared in step S2 into the reaction kettle, and stir and react at 0-5 °C for 1-2 h; S4: After the reaction in step S3 is completed, pour the reaction mixture into ice water for dilution to precipitate the nitrated product, filter and wash until the pH value is 7-9 to obtain nitrated humic acid; S5: Put the sulfonating agent into another reaction kettle, slowly drop the nitrated humic acid prepared in step S4 into the reaction kettle, and stir and react at 80-120 °C for 3-5 h; S6: After the reaction in step S5 is completed, cool the reaction mixture to room temperature, then slowly pour it into a large amount of ice water for dilution, then filter and wash until the pH value of the mixture is 7-9, and then dry it in a vacuum drying oven at 60-80 °C for 12-24 hours to obtain the modified humic acid.

6. The preparation method of the modified humic acid according to claim 5, wherein, The mass ratio of the humic acid to the carbonizing agent in step S1 is 1:3-5; the carbonizing agent is concentrated sulfuric acid.

7. The preparation method of the modified humic acid according to claim 5, wherein, The mass ratio of the carbonized humic acid to the nitrating agent in step S3 is 1:1.5-3.

8. The preparation method of the modified humic acid according to claim 5, characterized in that, The mass ratio of the nitrated humic acid to the sulfonating agent in step S5 is 1:0.8-2.

9. The application of the modified humic acid according to any one of claims 1-4, characterized in that, Compound the modified humic acid, sulfonated humic acid, and iron-loaded humic acid as an adsorbent for treating low-concentration ammonia nitrogen wastewater.

10. Use of the modified humic acid according to any one of claims 1-4, characterized in that, Compound the modified humic acid with chelated trace elements as a synergist for soil improvement and fertilizer synergism.